With the development of technology, portable terminals such as a mobile is phone, a PDA, a PMP, navigation, or a laptop computer further provide a DMB function, a wireless internet function, and a near-field-communication function between devices, in addition to a basic function such as a call function, a video/audio playing function, or a navigation function. Thus, the portable terminal has a plurality of antennas for radio communications, such as wireless internet or Bluetooth.
Recently, there is a tendency to apply an information interchange function between terminals, a payment function, a ticket reservation function, or a search function using near-field communication (i.e., NFC) to the portable terminal. To this end, an antenna module (i.e., NFC antenna module) for the portable terminal used in a near-field-communication method is mounted on the portable terminal. The used NFC antenna module is a kind of an electronic tag (RFID), is a non-contact near-field-communication module that uses a frequency band of about 13.56 Hz, and transmits data between terminals at a near distance of 10 cm. NFC is widely used for payment, transmission of article information in a supermarket or a general shop and travel information for visitors, a locking device for transportation or access control, etc.
The NFC antenna module is formed in a planar shape and then is mounted on a battery pack, a rear cover (or back cover), etc. By way of example, as illustrated in FIG. 1, the conventional NFC antenna module includes a shielding sheet 24 (e.g., metal plate such as a ferrite sheet) layered on a battery 22 of a portable terminal 10 and a radiator pattern 26 layered on the shielding sheet 24, and is mounted in a battery pack 20 of the portable terminal 10. Of course, as illustrated in FIG. 2, the NFC antenna module may further include a radiation patch 28 that is formed inside the radiator pattern 26 to be spaced apart from the radiator pattern 26.
Generally, since the rear cover of the portable terminal is made of a polycarbonate material, it does not affect the communication of the NFC antenna mounted on the battery pack, the rear cover or the like.
However, a recent trend (e.g., grip sensation, design trend such as appearance) preferred by consumers has increased a demand for a metallic rear cover. In this case, an antenna signal may be shielded by a metallic material, so that it may be impossible to perform near-field communication.